Hi,
I am trying to make my own solar powered garden light using a 4.5v 60mA solar panel incorporating a comparator with hystereis. The circuit works well, as the light level falls to a certain threshold the LED turns on. The solar panel charges the battery as well as acts as a sensor to turn the LED on.
My problem is as the battery slowly decreases the turn on time of the comparator drifts. I was thinking of using a zener diode to establish a constant reference voltage to the input of the comparator but since the desired turn on time of the solar panel is so low at around 0.15v a zener cant be used to establish a threshold.
I don’t know how clear this is but can anyone suggest anything?
I have included a attached drawing.
Thanks.
I am trying to make my own solar powered garden light using a 4.5v 60mA solar panel incorporating a comparator with hystereis. The circuit works well, as the light level falls to a certain threshold the LED turns on. The solar panel charges the battery as well as acts as a sensor to turn the LED on.
My problem is as the battery slowly decreases the turn on time of the comparator drifts. I was thinking of using a zener diode to establish a constant reference voltage to the input of the comparator but since the desired turn on time of the solar panel is so low at around 0.15v a zener cant be used to establish a threshold.
I don’t know how clear this is but can anyone suggest anything?
I have included a attached drawing.
Thanks.